##cl ##ization reaction was first demonstrated experimental ##ly by shop ##pe to be an intra ##mo ##le ##cular electro ##cy ##cl ##ization and is outlined below . activation of the ke ##tone by the acid catalyst generates a pen ##tad ##ien ##yl cat ##ion which undergoes a thermal ##ly allowed 4 ##π con ##rot ##atory electro ##cy ##cl ##ization as dictated by the woodward @ - @ hoffman rules . this generates an ox ##yal ##ly ##l cat ##ion which undergoes an elimination reaction to lose a β @ - @ hydrogen . subsequent taut ##ome ##rization of the en ##olate produces the cy ##cl ##open ##ten ##one product . as noted above , variants that devi ##ate from this template are known ; what designate ##s a
##clization reaction was first demonstrated experimentally by shoppe to be an intramolecular electrocyclization and is outlined below. activation of the ketone by the acid catalyst generates a pentadienyl cation which undergoes a thermally allowed 4π conrotatory electrocyclization as dictated by the woodward @ - @ hoffman rules. this generates an oxyallyl cation which undergoes an elimination reaction to lose a β @ - @ hydrogen. subsequent tautomerization of the enolate produces the cyclopentenone product. as noted above, variants that deviate from this template are known ; what designates a